Optical Signal Quality Monitoring Apparatus and Method

Abstract

A sampling optical pulse generation unit emits a sampling optical pulse. The sampling optical pulse has a period different from a predetermined offset time to integral multiplication of a clock period of a data signal, and the data signal modulates an optical signal of a monitoring target. An optical sampling unit performs sampling of the optical signal of the monitoring target using an electroabsorption optical modulator. The electroabsorption optical modulator has a characteristic in which an absorption index is changed with respect to light propagating through an optical path according to a level of an electric field. The optical signal of the monitoring target is input into one of two optical terminals of the electroabsorption optical modulator. The sampling optical pulse is input into another of the two optical terminals through a photocoupler. The absorption index with respect to the optical signal of the monitoring target is lowered by generating a mutual absorption saturation characteristic of the electroabsorption optical modulator when the sampling optical pulse is supplied, and the sampling of the optical signal of the monitoring target is performed to output an optical pulse signal from the other of the two optical terminals through the photocoupler.

Description

TECHNICAL FIELD[0001]The present invention relates to an optical signal quality monitoring apparatus and method, and particularly to optical signal quality monitoring apparatus and method which can correctly monitor quality of an optical signal modulated by a high-speed data signal.BACKGROUND ART[0002]In forming a network using the optical signal modulated by the data signal, it is necessary to monitor the quality of the optical signal propagating through the network with the optical signal quality monitoring apparatus.[0003]Generally, the optical signal quality monitoring apparatus obtains information on a waveform of a signal on a transmission path, and computes a value indicating the signal quality from the waveform information and supplies the computation result. Therefore, in the optical signal quality monitoring apparatus, it is extremely difficult to obtain the waveform information by a photodetector directly receiving the optical signal which is modulated by a data signal ha...

AI Technical Summary

Benefits of technology

[0017]In order to solve the problems of the conventional technique, an object of the invention is to provide optical signal quality monitoring apparatus and method, in which the sampling can accurately be performed to the information on the waveform of the high-speed optical signal with the high sampling efficiency and sufficient resolution, whereby the quality of the optical signal can correctly be monitored.

[0029]wherein, in order to prevent leakage of the sampling optical pulse (Ps) to a transmission path of the optical signal (Px) of the monitoring target, the sampling optical pulse (Ps) being input into the other of the two optical terminals (23a, 23b) of the electroabsorption optical modulator (23),

[0060]wherein, in order to prevent leakage of the sampling optical pulse (Ps) to a transmission path of the optical signal (Px) of the monitoring target, the sampling optical pulse (Ps) being input into the other of the two optical terminals (23a, 23b) of the electroabsorption optical modulator (23),

[0082]Therefore, the optical pulse having the narrow width can be used for the sampling, the sampling efficiency can be enhanced with respect to the optical signal of the monitoring target, and the information on the waveform can accurately be obtained even if the optical signal of the monitoring target is weak.

Problems solved by technology

Therefore, in the optical signal quality monitoring apparatus, it is extremely difficult to obtain the waveform information by a photodetector directly receiving the optical signal which is modulated by a data signal having a bit rate very high as tens of Gb / s.

However, in the technique disclosed in Patent Document 2, high-frequency impedance matching is required in the electric sampling pulse signal, and it is extremely difficult that a pulse width of the electric sampling pulse signal is stably narrowed without ringing.

Therefore, there is generated a new problem in that the information on the waveform of the optical signal modulated at tens of Gb / s cannot accurately be obtained with sufficient resolution.

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